Robust Bio-derived Polyoxometalate Hybrid for Selective Aerobic Oxidation of Benzylic C(sp³)–H Bonds

Abstract

Utilization of natural resources to construct functional catalytic materials for challenging organic reactions is of great importance in the chemical community, which has achieved significant attention. Herein, we describe the synthesis of a robust bio-derived polyoxometalate (POM) hybrid by the reaction of the naturally occurring phytic acid (PhyA) with MoO 3 , and the obtained hybrid was denoted PhyA−Mo. Systematic studies revealed that the multi-phosphate structure of PhyA enabled the synthesized PhyA−Mo to simultaneously possess a higher concentration of surface-active oxygen species and more negatively charged Mo sites, which played the role of catalytically active sites for aerobic oxidation. These two types of active sites together enabled the PhyA−Mo to show outstanding catalytic activity for aerobic oxidation of benzylic C(sp 3 )−H in different substrates to generate various carbonyl compounds without using any additional initiator. Importantly, the fact of realizing aerobic oxidation of benzylic C(sp 3 )−H bonds efficiently over POM-based materials in the absence of any radical initiator represented the main finding and the major breakthrough. Especially, this work provided a general and useful strategy to improve the catalytic performance of POM-based materials by using phosphoric acids containing multi-phosphate groups.

Solvent-modulated assembly of peptide and cerium functionalized gigantic {Mo120Ce6}2 dimers for high-efficiency photocatalytic oxidation

“…POMs have been well known for their good photocatalytic activities towards a variety of organic transformations derived from reversible redox properties and suitable ligand-to-metal charge transfer (LMCT). [64][65][66][67][68][69][70][71] Meanwhile, Ce III ion and Cebased compounds have recently emerged as privileged photocatalysts that can even efficiently deal with challenging C-H activation owing to facile redox shutter between the Ce(IV/III) couple. [72][73][74][75][76][77] In view of the presence of Ce ions in the frameworks of both 1 and 2, our efforts are directed towards exploring their potential for photocatalytic selective oxidation of sulfides to sulfoxides, key synthons used in fine chemicals, pesticides and pharmaceuticals, using O 2 as a terminal oxidant.…”

Boosting Solvent-Free Aerobic Oxidation of Benzylic Compounds into Ketones over Au-Pd Nanoparticles Supported by Porous Carbon

“…This would result in difficulty in product separation and purification, increasing energy consumption, and generating lots of poisonous and harmful wastewater in the production processes. In contrast, utilizing air or molecular oxygen as a sustainable oxidant, the aerobic oxidation of benzyl compounds in a solvent-free system is an ideal alternative to the above systems, and it promises to be a cost-efficient, low-energy consuming, and green oxidation process for the production of benzylic ketones [17].…”

Anderson-type polyoxometalate-based metal–organic framework as an efficient heterogeneous catalyst for selective oxidation of benzylic C–H bonds

“…[33][34][35][36][37][38] POMs have been well established as high-efficiency catalysts for oxidative transformation due to their inherent strong oxidizing ability, reversible multi-electron redox property, and high resistance to oxidative decomposition. [39][40][41][42][43][44] Integrated with NHPI, POM clusters such as Mo 72 V 30 can facilely catalyze the oxidation of benzylic alcohols and hydrocarbons to corresponding aldehydes or ketones. 45,46 Going beyond the homogeneous system, Installation of Cu-containing POM clusters within crystalline porous all-inorganic framework, the resulted heterogeneous catalyst can cooperate well with NHPI to promote biomimetic aerobic oxidation of aliphatic alcohols into carboxylic acids.…”